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The way in which the brain deals with sensory information relies not only on feedforward processing of signals from the periphery but also on feedback inputs. This is the case of the massive projection back from layer 6 in the visual cortex to the thalamus, for which, despite being the greatest single source of synaptic contacts, the functional role still(More)
Two types of thalamic nuclei have been recognized: first order, which relay information from subcortical sources, and higher order, which may relay information from one cortical area to another. We have recently shown that muscarinic agonists depolarize all first order and most higher order relay cells but hyperpolarize a significant proportion of higher(More)
The mammalian thalamus is composed of two types of thalamocortical relay. First order relays receive information from subcortical sources and relay it to cortex, whereas higher order relays receive information from layer 5 of one cortical area and relay it to another. Recent reports suggest that modulatory inputs to first and higher order relays may differ.(More)
We used an in vitro slice preparation of the lateral geniculate nucleus in cats and rats to study morphological correlates of triadic circuitry in relay cells. The three triadic elements involve a retinal synapse onto a GABAergic dendritic terminal of an interneuron, a synapse from the same retinal terminal onto a relay cell dendrite, and a synapse from the(More)
Coupled oscillations are hypothesized to organize the processing of information across distributed brain circuits. This idea is supported by recent evidence, and newly developed techniques promise to put such theoretical framework to mechanistic testing. We review evidence suggesting that individual oscillatory cycles constitute a functional unit that(More)
Thalamic input to the neocortex is crucial for sensory perception and constitutes the basis of complex awake behavior. Connections within the neocortex play an important role in internally generated neural activity, which is considered critical for memory retrieval and for the generation of imagery in our dreams. Modulatory neurotransmitters, such as(More)
BACKGROUND Low-frequency (delta/theta) oscillations in the thalamocortical system are elevated in schizophrenia during wakefulness and are also induced in the N-methyl-D-asparate receptor hypofunction rat model. To determine whether abnormal delta oscillations might produce functional deficits, we used optogenetic methods in awake rats. We illuminated(More)
The hippocampus is critical for the storage of new autobiographical experiences as memories. Following an initial encoding stage in the hippocampus, memories undergo a process of systems-level consolidation, which leads to greater stability through time and an increased reliance on neocortical areas for retrieval. The extent to which the retrieval of these(More)
The acute slice preparation can be a powerful tool to study brain networks that would otherwise be difficult to manipulate at the synaptic and cellular levels. In the first part of this chapter, we discuss the specific challenges of preparing brain slices to study neural networks, and we review solutions to overcome problems that can be faced during slice(More)